A brake pad comprises a support plate, preferably metal, obtained by punching, sintering or the like, and a layer of friction material adhering to the support plate.
After compaction and/or cross-linking and/or hardening of the friction material in the kiln, the friction layer must be finished to meet the geometric mounting tolerances on a brake caliper.
The finishing operation is carried out with rotary tools, such as grinders or milling cutters, which apply an action on the friction layer of a certain entity. Such action must be opposed in order to reduce the geometrical tolerances of the friction layer after the finishing. This requirement is particularly important because the shape and dimensions of the friction material must meet very tight tolerances required on the brake pad design. The finishing includes in particular the adjustment that allows the flatness of the surfaces delimiting the frictional layer to be defined. The finishing also comprises further abrasion operations for the removal of material carried out by means of milling cutters, also disk milling cutters, or grinders. For example, the finishing operation may comprise the realization of a groove in the friction layer by means of a disk milling cutter or grinder to subdivide a contact surface of the friction layer selectively cooperating in use with the brake disc into two or more areas.
Furthermore, the geometry of the friction layer may vary. After the finishing, the friction layer presents a main flat face substantially parallel, in use, to a brake disc. At the sides of the flat face, the friction layer may also present zones of variable thickness, in particular decreasing from the center of the pad towards the ends and/or the periphery. These zones are delimited by faces facing, in use, the disc and defining chamfers, for example flat chamfers, at constant angle. The chamfers may have different profiles, and present, for example, a sequence of flat faces at different inclinations to one another or a curvilinear ‘J’ form. It is therefore important that the finishing station is flexible to allow the creation of a variety of friction layer geometries.